I borrowed some PC2 8500 DDR2 Crossfire RAM for my old PC from a friend , and his computer was beeping. So i insert the ram and the same thing happens so i put one stick of his memory which has 1024mb and mine with 512 mb, and the pc booted up, everything was fine but the problem was still there when i put the other stick in. I cleaned it off with an eraser now the pc boots up and recognizes only one stick and npt the other but cpu z recognizes both of the sticks. Idk what to do.Here are the specs: Asus P5VD2-VM, Intel C2D E6600, Nvidia 7600GT, 400W MS industrial psu.